Planting zones · St. George, Utah
What Planting Zone Is St. George?
St. George is in USDA zone 8b. Mojave Desert edge at about 2,900 ft: just over 9 in. of precipitation, July highs near 102°F, and a frost-free season of about 239 days. Freezes still happen every winter (median last freeze mid-March), so frost-tender desert plants need siting care.
- USDA zone (2023)8b
- Coldest night (avg.)15 to 20°FZIP 84770
- Median last frostMar 1432°F
- Median first frostNov 1032°F
- Annual precipitation9.3 inches
- Frost-free season239 days
St. George hardiness zone by ZIP code
On the 2023 USDA Plant Hardiness Zone Map, the ZIP codes we sampled in St. George fall in zone 8b; 84770 (zone 8b) has an average annual extreme minimum of 15 to 20°F. Choose perennials, shrubs, and trees rated at least to zone 8.
| ZIP | Zone | Avg. coldest night |
|---|---|---|
| 84737 | 8b | 15 to 20°F |
| 84770 | 8b | 15 to 20°F |
| 84780 | 8b | 15 to 20°F |
| 84790 | 8b | 15 to 20°F |
Not listed? Look up any ZIP code.
Frost dates and when to plant
The median last spring frost (32°F) at St. George is Mar 14 and the median first fall frost is Nov 10, a typical frost-free season of about 239 days.
Plant container perennials and shrubs after the median last frost (Mar 14), or in early fall at least six weeks before the median first frost (Nov 10) so roots can settle in before the ground freezes.
Rainfall and heat in St. George
Average annual precipitation is 9.3 inches (St. George, 1991–2020), and 55% of it falls November–March. Summers are dry (June is the driest month), so plants lean on stored soil moisture and supplemental water through their first summer.
The average high in July is about 102°F and the average low in December is about 28°F, measured at about 2,860 ft.
That is why a zone rating alone isn't enough for a xeriscape here: pick plants that are both cold-hardy to zone 8 and rated very low or low water once established.
Low-water plants for St. George
82 plants in our database are hardy to zone 8 and suited to zone 8. Here are 12, driest first, across plant types.
'Desert Museum' Palo VerdeParkinsonia 'Desert Museum'Zones 8–11 · Very low water
Adam's Needle YuccaYucca filamentosaZones 4–10 · Very low water
Apache PlumeFallugia paradoxaZones 4–8 · Very low water
Blanket FlowerGaillardia aristataZones 3–8 · Very low water
Blue GramaBouteloua gracilisZones 3–10 · Very low water
Claret Cup CactusEchinocereus triglochidiatusZones 5–9 · Very low water
Hardy Ice PlantDelosperma cooperiZones 5–9 · Very low water
Blue Palo VerdeParkinsonia floridaZones 8–11 · Very low water
Havard AgaveAgave havardianaZones 5–9 · Very low water
Big SagebrushArtemisia tridentataZones 4–9 · Very low water
California FuchsiaEpilobium canum (syn. Zauschneria californica)Zones 8–10 · Very low water
Little BluestemSchizachyrium scopariumZones 3–9 · Very low water
Frequently asked questions
What planting zone is St. George?
St. George, UT is in USDA hardiness zone 8b on the 2023 USDA Plant Hardiness Zone Map, based on the ZIP codes we sampled (84737: 8b, 84770: 8b, 84780: 8b, 84790: 8b). In 84770, the average coldest night of the year is 15 to 20°F.
When is the last frost in St. George?
The median last spring frost (32°F) at St. George is Mar 14 and the median first fall frost is Nov 10, a typical frost-free season of about 239 days.
How much rain does St. George get?
Average annual precipitation is 9.3 inches (St. George, 1991–2020), and 55% of it falls November–March. Summers are dry (June is the driest month), so plants lean on stored soil moisture and supplemental water through their first summer.
Sources
- NOAA NCEI U.S. Climate Normals 1991–2020, St. George (USC00427516). ncei.noaa.gov
- USDA ARS 2023 Plant Hardiness Zone Map, by ZIP. planthardiness.ars.usda.gov